diff --git a/litellm/router_strategy/tag_based_routing.py b/litellm/router_strategy/tag_based_routing.py index d4f46e94579..a8774bc06c7 100644 --- a/litellm/router_strategy/tag_based_routing.py +++ b/litellm/router_strategy/tag_based_routing.py @@ -434,6 +434,36 @@ def _inherited_constraint_sets( return frozenset(inherited_required), frozenset(inherited_excluded) +def _inherited_full_tags(inherited_tags: object, routing_prefix: str) -> frozenset[str]: + # Policy tags exempt request-tag scoping regardless of prefix (see + # _scope_to_confirmed_and_inherited_tags); matched by exact rewritten form, + # not bare value, so a caller can't exempt an unrelated tag by reusing a + # policy tag's bare value under a different "&"/"!" marker. + if not isinstance(inherited_tags, (list, tuple)): + return frozenset() + return frozenset(_strip_routing_prefix(inherited_tags, routing_prefix)[0]) + + +def _scope_to_confirmed_and_inherited_tags( + rewritten_tags: tuple[str, ...], + original_tags: Sequence[str], + inherited_tags: object, + routing_prefix: str, +) -> tuple[str, ...]: + # Once a prefix is configured, an unprefixed request tag is noise, not a + # routing signal -- except a tag the caller explicitly prefixed, or one + # policy already contributed via inherited_tags (not caller-controlled, so + # exempt regardless of prefix). Matching the full rewritten tag rather than + # _strip_routing_prefix's bare-value `confirmed` return (used elsewhere for + # the "known required tag" fail-open check) avoids exempting an unrelated + # tag that happens to share a bare value under a different marker. + confirmed_full_tags: Final = frozenset( + rewritten for rewritten, original in zip(rewritten_tags, original_tags) if original.startswith(routing_prefix) + ) + inherited_full_tags: Final = _inherited_full_tags(inherited_tags, routing_prefix) + return tuple(t for t in rewritten_tags if t in confirmed_full_tags or t in inherited_full_tags) + + def _tag_known_to_group( llm_router_instance: LitellmRouter, model: str, @@ -532,7 +562,14 @@ async def get_deployments_for_tag( # caller-declared routing directive, exempt from the "maybe foreign to this # group" heuristics that unprefixed tags still go through unchanged below. rewritten_tags, routing_confirmed = _strip_routing_prefix(request_tags or [], routing_prefix) - required_tags, positive_tags, excluded_patterns = _split_tags(rewritten_tags) + scoped_tags: Final = ( + _scope_to_confirmed_and_inherited_tags( + rewritten_tags, request_tags or (), metadata.get("inherited_tags"), routing_prefix + ) + if routing_prefix + else rewritten_tags + ) + required_tags, positive_tags, excluded_patterns = _split_tags(scoped_tags) inherited_required_set, inherited_excluded_set = _inherited_constraint_sets( metadata.get("inherited_tags"), routing_prefix ) diff --git a/tests/test_litellm/router_strategy/test_router_tag_routing.py b/tests/test_litellm/router_strategy/test_router_tag_routing.py index 16c641b8d29..81762ee0d1f 100644 --- a/tests/test_litellm/router_strategy/test_router_tag_routing.py +++ b/tests/test_litellm/router_strategy/test_router_tag_routing.py @@ -3160,3 +3160,203 @@ async def test_chat_request_carrying_litellm_metadata_still_routes_on_proxy_merg ) assert deployment["model_info"]["id"] == "team-a-deployment" + + +# --- unprefixed request tags must be a no-op once tag_routing_prefix is +# configured (GitHub issue #39901) --- + + +def _untagged_single_deployment_router(tag_routing_prefix: str = "route:") -> litellm.Router: + return litellm.Router( + model_list=[ + { + "model_name": "chat", + "litellm_params": { + "model": "gpt-4o", + "api_base": "https://exampleopenaiendpoint-production.up.railway.app/", + }, + "model_info": {"id": "only-deployment"}, + }, + ], + enable_tag_filtering=True, + tag_routing_prefix=tag_routing_prefix, + ) + + +@pytest.mark.asyncio() +async def test_unprefixed_request_tag_is_noop_when_prefix_configured(): + # Zero deployment tags in the group; an unrelated tag must not raise. + router = _untagged_single_deployment_router() + + response = await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": ["user_id:234"]}, + mock_response="hi", + ) + + assert response._hidden_params["model_id"] == "only-deployment" + + +@pytest.mark.asyncio() +async def test_no_tags_still_noop_when_prefix_configured(): + # Baseline: no tags at all must keep working identically. + router = _untagged_single_deployment_router() + + response = await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": []}, + mock_response="hi", + ) + + assert response._hidden_params["model_id"] == "only-deployment" + + +@pytest.mark.asyncio() +async def test_prefixed_tag_still_raises_when_unresolvable(): + # A genuinely prefixed, unresolvable tag must still raise. + router = _untagged_single_deployment_router() + + with pytest.raises(Exception, match='Not allowed to access model due to tags configuration\\.') as exc_info: + await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": ["route:quality:nonexistent"]}, + mock_response="hi", + ) + + from litellm.types.router import RouterErrors + + assert RouterErrors.no_deployments_with_tag_routing.value in str(exc_info.value) + + +@pytest.mark.asyncio() +async def test_unprefixed_tag_still_raises_when_no_prefix_configured(): + # Backward compat: no prefix configured, so the old behavior is unchanged. + router = _untagged_single_deployment_router(tag_routing_prefix="") + + with pytest.raises(Exception, match='Not allowed to access model due to tags configuration\\.') as exc_info: + await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": ["user_id:234"]}, + mock_response="hi", + ) + + from litellm.types.router import RouterErrors + + assert RouterErrors.no_deployments_with_tag_routing.value in str(exc_info.value) + + +@pytest.mark.asyncio() +async def test_inherited_required_tag_unaffected_by_prefix_scoping(): + # An unprefixed policy "&" requirement in inherited_tags must still apply. + router = _eu_region_router() + router.update_settings(tag_routing_prefix="route:") + + response = await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": ["®ion:eu"], "inherited_tags": ["®ion:eu"]}, + mock_response="hi", + ) + + assert response._hidden_params["model_id"] == "eu-1" + + +@pytest.mark.asyncio() +async def test_inherited_excluded_tag_unaffected_by_prefix_scoping(): + # Same, for a "!" exclusion, without exhausting the pool -- proves the + # primary candidate computation honors it, not just the fail-open floor. + router = _eu_region_router() + router.update_settings(tag_routing_prefix="route:") + + response = await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": ["!region:us"], "inherited_tags": ["!region:us"]}, + mock_response="hi", + ) + + assert response._hidden_params["model_id"] == "eu-1" + + +@pytest.mark.asyncio() +async def test_foreign_tag_ignored_alongside_inherited_constraint_when_prefix_configured(): + # A foreign tag and an inherited requirement in the same request: the + # foreign tag must be ignored. No allow_fail_open (unlike _eu_region_router) + # so a leaked foreign tag can't self-heal via the fail-open floor. + router = litellm.Router( + model_list=[ + { + "model_name": "chat", + "litellm_params": { + "model": "gpt-4o", + "api_base": "https://exampleopenaiendpoint-production.up.railway.app/", + "tags": ["region:eu"], + }, + "model_info": {"id": "eu-1"}, + }, + { + "model_name": "chat", + "litellm_params": { + "model": "gpt-4o-mini", + "api_base": "https://exampleopenaiendpoint-production.up.railway.app/", + "tags": ["region:us"], + }, + "model_info": {"id": "us-1"}, + }, + ], + enable_tag_filtering=True, + ) + router.update_settings(tag_routing_prefix="route:") + + response = await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": ["®ion:eu", "user_id:234"], "inherited_tags": ["®ion:eu"]}, + mock_response="hi", + ) + + assert response._hidden_params["model_id"] == "eu-1" + + +@pytest.mark.asyncio() +async def test_unprefixed_tag_cannot_piggyback_via_bare_value_collision_with_confirmed_tag(): + # Exemption is keyed on the exact tag, not its bare value: a confirmed + # "route:region:eu" must not exempt an unrelated "!region:eu" sharing the + # same bare value under a different marker. + router = litellm.Router( + model_list=[ + { + "model_name": "chat", + "litellm_params": { + "model": "gpt-4o", + "api_base": "https://exampleopenaiendpoint-production.up.railway.app/", + "tags": ["region:eu"], + }, + "model_info": {"id": "eu-1"}, + }, + { + "model_name": "chat", + "litellm_params": { + "model": "gpt-4o-mini", + "api_base": "https://exampleopenaiendpoint-production.up.railway.app/", + "tags": ["region:us"], + }, + "model_info": {"id": "us-1"}, + }, + ], + enable_tag_filtering=True, + tag_routing_prefix="route:", + ) + + response = await router.acompletion( + model="chat", + messages=[{"role": "user", "content": "hi"}], + metadata={"tags": ["route:region:eu", "!region:eu"]}, + mock_response="hi", + ) + + assert response._hidden_params["model_id"] == "eu-1"